Hi,
On 2024/4/23 16:05, Krzysztof Kozlowski wrote:
On 22/04/2024 21:19, Sui Jingfeng wrote:
Otherwise when compiled as module, this driver will not be probed on
non-DT environment. This is a fundamential step to make this driver
truely OF-independent.
NAK.
:( ...
You should not need MODULE_ALIAS() in normal cases. If you need it,
usually it means your device ID table is wrong (e.g. misses either
entries or MODULE_DEVICE_TABLE()). MODULE_ALIAS() is not a substitute
for incomplete ID table.
I think I could give you a reason.
1) When compile this driver into linux kernel
This driver will be probed if we create a platform device manually with the name
"tfp410".
This is also true for the display-connector
driver(drivers/gpu/drm/bridge/display-connector.c),
see patch 0005 of this series and the simple-bridge
driver(drivers/gpu/drm/bridge/simple-bridge.c)
see patch 0003 of this series.
2) But when compile this driver as module, creating a platform device manually
with the same name
*won't* make those platform driver probed. I think, this is *inconsistent
behavior*. Therefore, I
add MODULE_ALIAS() to keep the behavior consistent. That is, a driver, should
be able to be probed
regardless it is compile as a kernel module or it is built into the kernel.
Just check your aliases and look what is there. You already have
i2c:tfp410 alias.
Right, but the i2c:tfp410 alias only guarantee the driver can be probed
successfully
when tfp410 working as I2C slave. tfp410 can also works as a transparent bridge.
If you need platform one, for some reason, explain
what is your matching path and add appropriate ID table. With that
explanation, of course.
When tfp410 works as a transparent bridge. The device itself is just a platform
device.
similar with the display-connector.c and simple-bridge.c.
It is not discoverable by the system on non-DT environment, this is the root
problem.
I said the various display bridges drivers are fully DT dependent, Dimtry
didn't agree!
He said "I can not agree here. It doesn't depend on DT." and then asks me to
developing
some other solution witch could preserve code sharing. So here it is.
Best regards,
Krzysztof
--
Best regards,
Sui
